You can also use spamassassin to blacklist email address. Just add to your own spamassassin configuration or to /etc/mail/spamassassin/local.cf file:# vi /etc/mail/spamassassin/local.cf Append blacklist as follows:blacklist_from user@abadboy.com Save and close the file. Restart spamassassin:# /etc/init.d/spamassassin restart